JP2003254172A - Evaporative fuel processing mechanism diagnostic device - Google Patents

Abstract

(57) [Summary] [Problem] Diagnosis of an evaporative fuel processing mechanism capable of accurately detecting a decrease in response of a switching valve so that appropriate measures can be taken against the decrease in response of the switching valve. Providing equipment. An electric pump that repeats communication / blocking between the evaporation path 4 and the atmosphere side in order to gradually reduce the pressure in the evaporation path 4 after performing leak diagnosis by increasing the pressure in the evaporation path 4 The switching valve in the module 10 is forcibly switched. In this process, when the switching valve shifts from the communication state to the shut-off state, if the responsiveness of the switching valve is lowered, a delay occurs in the transition, and the pressure in the evaporation path 4 in a predetermined period after the transition starts. The decrease amount Pd is kept large. By evaluating the responsiveness of the switching valve based on the pressure drop amount Pd, it is possible to accurately detect the responsiveness of the switching valve.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a failure diagnosis device for an evaporated fuel processing mechanism.

[0002]

2. Description of the Related Art Conventionally, in vehicles such as automobiles,
A fuel supply system of an internal combustion engine mounted as a prime mover, for example, an evaporative fuel processing mechanism having an evaporation path for sending evaporative fuel generated in a fuel tank to an intake system of the internal combustion engine is provided. The evaporation path of this mechanism includes a canister provided with an adsorbent that adsorbs evaporated fuel, and a purge passage that connects the canister to the intake system of the internal combustion engine. During operation of the internal combustion engine, the negative pressure generated in the intake system of the engine is used to introduce air in the atmosphere into the canister through the atmosphere passage, and along with this air, the evaporated fuel in the canister passes through the purge passage. Is sent to the intake system. As a result, the vaporized fuel is burned in the internal combustion engine and is processed without being released into the atmosphere.

In such an evaporative fuel processing mechanism, in order to secure the reliability of suppressing the emission of the evaporative fuel into the atmosphere, the evaporative fuel from the evaporative route due to perforation, laceration, defective sealing, etc. The leakage is regularly diagnosed. Such leak diagnosis, for example, pressurizes the evaporative pathway in a closed state,
It will be performed based on the pressure state in the evaporation path at that time. The closing of the evaporation path from the atmosphere side of the same path is realized by switching a switching valve that performs a switching operation to bring the atmosphere passage into a communication state or a blocking state.

Immediately after the leak diagnosis is performed as described above, the pressure inside the evaporation path is higher than the atmospheric pressure. Therefore, the switching path is used to move the evaporation path to the atmosphere side in order to reduce the pressure. The gas in the evaporation path is discharged to the atmosphere side via the canister with the fuel vapor being removed.

However, when the gas is rapidly released from the evaporation path to the atmosphere side, the flow rate and flow velocity of the gas increase, and the adsorption efficiency of the evaporated fuel in the canister decreases. Therefore, when the gas passes through the canister, the vaporized fuel contained in the gas cannot be adsorbed, or the vaporized fuel already adsorbed in the canister is released from the canister by the passage of the gas,
Gas containing evaporated fuel may be released to the atmosphere.

Therefore, for example, Japanese Patent Laid-Open No. 2000-20505.
As disclosed in Japanese Unexamined Patent Publication No. 8 (1998), it has been considered to control the switching valve so that the above-described gas release is gradually performed after the leak diagnosis. By controlling the switching valve in this way, the flow rate and flow velocity of the gas released from the evaporation path to the atmosphere side after the leak diagnosis is suppressed from increasing, and the gas containing the evaporated fuel enters the atmosphere side. The release can be suppressed.

[0007]

However, when the responsiveness in controlling the switching valve is lowered for some reason such as deterioration of the switching valve, the gas is gradually released from the evaporation path. Even if you try to operate the switching valve,
That is difficult to achieve. Therefore, when the responsiveness of the switching valve is reduced, if the reduction is detected and appropriate measures are not taken, when controlling the switching valve after leak diagnosis to release the gas in the evaporation path to the atmosphere side, The gas containing the evaporated fuel is released to the atmosphere side.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a responsiveness of a switching valve so that appropriate measures can be taken against a reduction in the responsiveness of the switching valve. An object of the present invention is to provide a diagnostic device for an evaporated fuel processing mechanism that can accurately detect a decrease.

[0009]

[Means for Solving the Problems] Means for achieving the above-mentioned objects and their effects will be described below. In order to achieve the above object, in the invention according to claim 1, an evaporation path for sending evaporated fuel generated in a fuel supply system of an internal combustion engine to an intake system of the engine and a communication path between the evaporation path and the atmosphere side are cut off. It is applied to an evaporative fuel processing mechanism including a switching valve that can be switched as needed, and the leak is diagnosed based on the pressure state when the evaporative path and the atmosphere side are shut off by the switching valve and the inside of the path is pressurized in this state. In the diagnostic device of the evaporated fuel processing mechanism that controls the switching valve so that the gas in the evaporation path is gradually discharged to the atmosphere side after the diagnosis, in the evaporation path from the evaporation path to the atmosphere side after the leak diagnosis. Control means for controlling the switching valve so as to shut off the evaporation path and the atmosphere side when the gas is being discharged; and the switching valve by the control means. Based on the change in pressure in the evaporation route when it is controlled to cut off the atmosphere side, and so and a evaluation means for evaluating the response of the switching valve.

When the switching valve is controlled by the control means so as to shut off the evaporation path from the atmosphere side, if the responsiveness of the switching valve is lowered, the pressure drop amount in the evaporation path remains large. Will be maintained. Therefore, by evaluating the responsiveness of the switching valve based on the pressure state in the evaporation path at this time, it is possible to accurately detect the responsiveness of the switching valve, and take appropriate measures against the responsiveness deterioration. You will be able to take action.

According to a second aspect of the present invention, in the first aspect of the present invention, the evaluation means is configured so that when the control means controls the switching valve to shut off the evaporation path from the atmosphere side, Based on the fact that the amount of pressure decrease in the path continues to be equal to or greater than a predetermined value for a predetermined period, it is evaluated that the responsiveness of the switching valve is deteriorated.

When the responsiveness of the switching valve is low,
Since the amount of pressure decrease in the evaporation path continues to be equal to or more than the predetermined value during the predetermined period, it is possible to accurately evaluate that the responsiveness of the switching valve is reduced based on that. Then, by evaluating the responsiveness of the switching valve in this manner, it becomes possible to accurately detect a decrease in the responsiveness of the switching valve.

According to the invention of claim 3, claim 1 or 2
In the invention described above, the control means establishes communication between the evaporation path and the atmosphere side before controlling the switching valve so as to shut off the evaporation path and the atmosphere side for the responsiveness evaluation of the switching valve. The switching valve is forcibly controlled so that

According to the above construction, when the response of the switching valve is evaluated, the switching valve is first controlled so as to communicatively connect the evaporation path and the atmosphere side, and then the evaporation path and the atmosphere side are shut off. Since it is controlled as described above, the pressure change in the evaporation path at that time becomes apparent. Therefore,
The responsiveness of the switching valve based on the pressure change can be accurately evaluated.

According to a fourth aspect of the present invention, in the invention according to any one of the first to third aspects, the control means causes the evaporation route and the atmosphere side to communicate with each other when the leak diagnosis is completed. The switching valve is forcibly controlled.

According to the above construction, when the leak diagnosis is completed, the switching valve is controlled so as to forcibly shut off the evaporation path and the atmosphere side, so that immediately after that, the evaporation path and the atmosphere side are shut off. By controlling the switching valve in this manner, it is possible to evaluate the decrease in responsiveness. Therefore, the responsiveness of the switching valve can be evaluated at an early stage after the leak diagnosis is completed, and the decrease in responsiveness can be detected promptly.

According to a fifth aspect of the present invention, in the invention according to any one of the first to fourth aspects, the control means connects or disconnects the evaporation path and the atmosphere side after the leak diagnosis is completed. The switching valve is controlled so as to be repeated every predetermined period.

According to the above construction, rapid release of gas from the evaporation path to the atmosphere side is suppressed by periodically opening and closing the communication between the evaporation path and the atmosphere side by the switching valve after the leak diagnosis. be able to. Furthermore, when the switching valve is controlled so as to block the evaporative passage and the atmosphere side in the periodic communication / shutoff, the responsiveness of the switching valve is evaluated based on the pressure change in the evaporative path. Therefore,
It is possible to evaluate the responsiveness of the switching valve while suppressing the sudden release of gas from the evaporation path to the atmosphere side as much as possible.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment in which the present invention is embodied in a diagnostic device for an evaporated fuel processing mechanism mounted on an automobile will be described below with reference to FIGS.

The evaporated fuel processing mechanism shown in FIG. 1 is provided with an evaporation path 4 for sending evaporated fuel generated in a fuel supply system of the engine 1, for example, a fuel tank 2 to an intake passage 3 of the engine 1. In the evaporation path 4, a canister 5 provided with an adsorbent that adsorbs the evaporated fuel, a vapor passage 6 that introduces the evaporated fuel generated in the fuel tank 2 into the canister 5, and the evaporated fuel in the canister 5 together with air. A purge passage 7 that is sent to the intake passage 3 is included.

The evaporated fuel generated in the fuel tank 2 passes through the vapor passage 6 and is once adsorbed by the adsorbent in the canister 5. Then, when the engine is operating, air from the outside is introduced into the canister 5 through the atmosphere passage 8 by the action of the negative pressure generated in the intake passage 3. Along with this air, the evaporated fuel in the canister 5 is sent to the intake passage 3 as purge gas through the purge passage 7 due to the negative pressure.
The engine 1 is burned and processed.

The purge passage 7 is provided with a purge control valve 9 which is opened and closed to adjust the flow rate of the purge gas. Further, the atmosphere passage 8 is provided with an electric pump module 10 for forcibly sending air into the evaporation path 4 when diagnosing a leak of evaporated fuel or the like from the evaporation path 4. The purge control valve 9 and the electric pump module 10 are an electronic control unit (ECU) 1 mounted on an automobile.
The drive is controlled by 1.

The detailed structure of the electric pump module 10 will be described with reference to FIGS. 2 and 3.
The electric pump module 10 includes a switching valve 12 that performs a switching operation to switch the atmosphere passage 8 between a communication state and a cutoff state.
Is equipped with. The switching valve 12 is switched as shown in FIG. 2 when the atmosphere passage 8 is in the communication state, and is switched as shown in FIG. 3 when the atmosphere passage 8 is in the cutoff state. By switching the switching valve 12 as described above, the canister 5 (evaporation path 4) and the atmosphere side are communicated / blocked. Then, the switching valve 12 shuts off the canister 5 from the atmosphere side, and the purge control valve 9 is closed (shut-off state).
Is a closed space.

Further, the switching valve 12 is switched so that the atmosphere passage 8 is shut off (FIG. 3), that is, when the canister 5 and the atmosphere side are shut off, the canister 5 is opened.
The (evaporation path 4) and the electric air pump 13 are communicated with each other. A check valve 15 is provided between the electric air pump 13 and the switching valve 12 to prevent gas from flowing from the evaporation path 4 side to the pump 13 side. Further, a pressure sensor 16 is provided between the check valve 15 and the switching valve 12, and the evaporation path 4 and the electric air pump 13 are connected to each other by the switching valve 1.
When the communication is established via 2, the pressure sensor 16 outputs a signal corresponding to the pressure in the evaporation path 4 to the electronic control unit 11.

The electric air pump 13 is driven and controlled by the electronic control unit 11, and when it is driven with the evaporation path 4 closed as described above, air is sent to the evaporation path 4 and the same operation is performed. The inside of the path 4 is pressurized.
In this way, when pressurizing the inside of the evaporation path 4,
If there is a hole in and there is a leak (leak), the pressure obtained based on the detection signal from the pressure sensor 16 becomes lower than in the normal state. Therefore, it becomes possible to determine whether or not a leak has occurred in the evaporation path 4 based on whether or not this pressure is lower than the predetermined reference value P.

The electric air pump 13 is also in communication with the bypass passage 14 via the check valve 15. This bypass passage 14 bypasses the switching valve 12, and the canister 5 (evaporation path 4) and the switching valve 12 are bypassed in the atmosphere passage 8.
It is connected to the part located between and. Further, the flow of gas from the bypass passage 14 side to the electric air pump 13 side is suppressed by the check valve 15. Therefore, when the electric air pump 13 is driven in a state where the evaporation path 4 and the atmosphere side are communicated with each other by the switching valve 12 (FIG. 2), the air discharged from the pump 13 passes through the bypass passage 14 and the atmosphere passage 8 Is discharged to the atmosphere through the atmosphere passage 8. At this time, the pressure between the bypass passage 14 and the check valve 15 rises toward a predetermined value according to the inner diameter of the bypass passage 14 and then converges to that value.

This pressure is obtained based on the detection signal from the pressure sensor 16, and the evaporation path 4 having a hole having the same diameter as the inner diameter of the bypass passage 14 is closed as described above and pressurized by the electric air pump 13. Same route 4 when it is assumed that
It is close to the internal pressure. Therefore, as described above, when the presence or absence of the leak in the evaporation path 4 is determined, the reference value P used for the determination can be obtained based on the pressure between the bypass passage 14 and the check valve 15. . In this embodiment, a reference hole 17 having an inner diameter of 0.5 mm is formed in the bypass passage 14 so that the pressure becomes a value suitable for obtaining the reference value P.

Next, the leak diagnosis of the evaporation route 4 will be described with reference to the time chart of FIG. When a predetermined time has elapsed after the engine was stopped, the electronic control unit 11 is automatically activated. Immediately after the activation of the electronic control unit 11, the switching valve 12 is in a state (communication state) in which the evaporation path 4 and the atmosphere side are in communication, and the pressure in the evaporation path 4 is equal to the atmospheric pressure. After that, the electronic control unit 1
Leak diagnosis is executed through 1. In this leak diagnosis, first, the above-mentioned reference value P is set in predetermined periods T1 and T2 after the diagnosis is started, and in the following predetermined period T3, whether or not there is a leak from the evaporation route 4 is used by using the reference value P. To be judged. Hereinafter, the processing in the predetermined periods T1 and T2 and the processing in the predetermined period T3 will be described.

[Predetermined period T1, T2] During the predetermined period T1, the switching valve 1 is operated while the electric air pump 13 is stopped.
2 is switched to a state in which the evaporation path 4 and the atmosphere side are blocked as shown in FIG. 3 (blocking state),
The purge control valve 9 is closed. As a result, the evaporation route 4
Will be closed. Then, based on the pressure change amount ΔP in the evaporation path 4 during the predetermined period T1, the pressure increase rate due to the generation of evaporated fuel in the closed evaporation path 4 is calculated.

Thereafter, in a predetermined period T2, the switching valve 12 is switched to a state (communication state) in which the evaporation path 4 and the atmosphere side are communicated with each other as shown in FIG. 2, and the electric air pump 13 is driven. Air is sent into the bypass passage 14. In this state, the bypass passage 1
4 and the check valve 15 increase in pressure toward a predetermined value P1 corresponding to the diameter of the reference hole 17, and then the predetermined value P1.
Converge to. Bypass passage 14 and check valve 15 at this time
The pressure (predetermined value P1) between the inside of the bypass passage 14 and the reference hole 17 of the bypass passage 14 is the same as the reference passage 17 in the same passage 4 assuming that the evaporation passage 4 is closed and pressurized by the electric air pump 13. It is close to the pressure of. Therefore, it is possible to obtain the reference value P based on the pressure (predetermined value P1) between the bypass passage 14 and the check valve 15.

However, with respect to the reference value P, the optimum value changes in accordance with the pressure increase accompanying the generation of evaporated fuel in the closed evaporation path 4. Therefore, when the reference value P is obtained, in addition to the pressure (predetermined value P1) between the bypass passage 14 and the check valve 15, the rate of pressure increase calculated in the predetermined period T1 is also taken into consideration. That is, the amount of pressure increase associated with the generation of evaporated fuel in the predetermined period T3 is calculated based on the pressure increase rate, and the reference value P is obtained using the amount of pressure increase and the predetermined value P1. As a result, the reference value P is made appropriate as a value used for the determination of leakage from the evaporation route 4. That is, the reference value P is set to a low-pressure side value when the pressure increase amount is small, and is set to a high-pressure side value as the pressure increase amount is large.

[Predetermined Period T3] In the predetermined period T3, the switching valve 12 is switched to the state in which the evaporation path 4 and the atmosphere passage 8 are shut off while the electric air pump 13 is still driven. As a result, the evaporation path 4 is closed and pressurized, so that the pressure in the path 4 gradually increases. Then, if the pressure becomes higher than the reference value P as shown by the solid line in FIG. 4 before the elapse of the predetermined period T3, it is determined that no leak occurs in the evaporation route 4. Further, if the pressure does not reach the reference value P as shown by the alternate long and short dash line in FIG. 4 before the elapse of the predetermined period T3, it is determined that the leak occurs in the evaporation route 4.

By the way, after the leak diagnosis is completed after the elapse of the predetermined period T3, the pressure in the evaporation path 4 is high, and therefore the switching valve 12 is used to reduce the pressure.
Is switched to a state in which the evaporation path 4 and the atmosphere side communicate with each other, for example. In this state, the gas in the evaporation path 4 is released to the outside through the atmosphere passage 8 after removing the evaporated fuel via the canister 5, and the pressure in the evaporation path 4 is reduced.

However, when the gas is rapidly released from the evaporation path 4 to the atmosphere side, the flow rate and the flow velocity of the gas are increased and the adsorption efficiency of the evaporated fuel in the canister 5 is lowered. Therefore, when the gas passes through the canister 5, the vaporized fuel contained in the gas can no longer be adsorbed, or the vaporized fuel already adsorbed by the canister 5 is separated from the canister 5 by the passage of the gas. , Gas containing vaporized fuel may be released to the atmosphere side.

In order to suppress this, the switching valve 12 is operated so as to release the gas in such a manner that the pressure in the evaporation path 4 gradually decreases to atmospheric pressure over, for example, 1 to 2 minutes. It is also possible to control. Such a switching valve 1
As the control of 2, the control of the switching valve 12 that repeats communication / interruption between the evaporation path 4 and the atmosphere side every predetermined cycle, for example, the switching valve 12 that repeats communication / interruption in which the communication state continues for 195 ms after the interruption state continues for 65 ms Control is forced to be executed.

By controlling the switching valve 12 in this way,
The gas is gradually released from the evaporation path 4 to the atmosphere side. Therefore, after the leak diagnosis, the total amount of gas (gas release amount) released from the evaporation route 4 to the atmosphere side gradually increases as shown in FIG.
The internal pressure gradually decreases as shown in FIG. Therefore, as the gas is rapidly released from the evaporation path 4 to the atmosphere side, it is possible to suppress the gas containing the evaporated fuel from being released to the atmosphere side as described above.

However, if the responsiveness when controlling the switching valve 12 is lowered for some reason such as deterioration of the switching valve 12 as described above, the gas is gradually released from the evaporation path 4. Even if the switching valve 12 is operated, it is difficult to realize it. That is, when the responsiveness of the switching valve 12 is lowered, for example, when the switching valve 12 is switched from the communication state to the cutoff state, the transition to the cutoff state is delayed, and the gas from the evaporation path 4 to the atmosphere side is delayed. The release of is sudden. As a result, the amount of gas released after the leak diagnosis suddenly increases as shown in FIG. 7, and the pressure in the evaporation path 4 also sharply decreases as shown in FIG. It will be released to the atmosphere side from the evaporation route 4.

Therefore, when the responsiveness of the switching valve 12 is deteriorated, if the deterioration is detected and appropriate countermeasures are not taken, the switching valve 12 is controlled after the leakage diagnosis to control the evaporation path 4.
When the gas inside is gradually released to the atmosphere side, a problem occurs that the gas containing evaporated fuel is released to the atmosphere side.

In view of this, in the present embodiment, after the leak diagnosis, the evaporation path 4 and the atmosphere passage 8 are connected to each other from the state in which the switching valve 12 is controlled so as to discharge the gas from the evaporation path 4 to the atmosphere side (communication state). Shutdown state (shutoff state)
When the switching valve 12 is switched to, the responsiveness of the switching valve 12 is evaluated based on the pressure change in the evaporation path 4. By performing such an evaluation, it is possible to accurately detect a decrease in the responsiveness of the switching valve 12.

When the responsiveness of the switching valve 12 is detected, the electronic control unit 11 indicates that the responsiveness of the switching valve 12 has been evaluated, for example, the abnormal lamp 18 (see FIG. Notify the driver etc. by lighting 1). In this way, by notifying that the responsiveness of the switching valve 12 has deteriorated, it is possible to promptly take appropriate measures against the responsiveness deterioration.

Here, the responsiveness evaluation of the switching valve 12 will be specifically described with reference to FIGS.
9 and 11 are time charts showing changes in pressure in the evaporation path 4 when there is an instruction to switch the switching valve 12 from the open state to the closed state in the control of the switching valve 12 after the leak diagnosis. Is. This pressure changes as shown in FIG. 9 when the responsiveness of the switching valve 12 is not lowered, and changes as shown in FIG. 11 when the responsiveness of the switching valve 12 is lowered.

When controlling the switching valve 12, as shown in FIG. 9 and FIG.
As shown in 1, when the switching valve 12 that has been in the communication state for 65 ms is instructed to switch to the shutoff state (timing a), the switching valve 12 shifts to the shutoff state. . When the switching valve 12 is controlled to be in the shutoff state (during 195 ms), the pressure decrease amount of the evaporation path 4 is calculated at timings b, c, and d every 65 ms. That is, at timings b, c, and d, the pressure difference between timings a and b, the pressure difference between timings b and c, and the pressure difference between timings c and d are calculated, and these pressure differences are calculated as timing b. , C, d pressure drop Pd
It is said that

Then, the responsiveness of the switching valve 12 is evaluated according to the pressure decrease amount Pd at the timings b, c and d. When the responsiveness of the switching valve 12 is not deteriorated, the switching valve 1
Since there is no delay in the shift of the switching valve 2 to the shutoff state, the pressure drop in the evaporation path 4 at that time becomes small as the switching valve 12 shifts to the shutoff state. Therefore, for example, as shown in FIG. 10, the pressure decrease amount Pd at the timings b, c, d
If any one of them is smaller than the judgment value X,
It is evaluated that the responsiveness of the switching valve 12 has not deteriorated.

On the other hand, when the responsiveness of the switching valve 12 is lowered, the changeover of the switching valve 12 to the shut-off state is delayed, so that the pressure drop in the evaporation path 4 at that time is unlikely to be small. Therefore, as shown in FIG. 12, all the pressure decrease amounts Pd at the timings b, c, and d are larger than the determination value X, and a predetermined period (195 ms of start of control of the switching valve 12 to the closed state) If the pressure decrease amount Pd continues to be equal to or less than the determination value X during (interval), it is evaluated that the responsiveness of the switching valve 12 is decreasing.

Next, the procedure for evaluating the responsiveness of the switching valve 12 and detecting the decrease in the responsiveness of the switching valve 12 will be described with reference to the flowchart of FIG. 13 showing the switching valve evaluation routine. This switching valve evaluation routine is performed by the electronic control unit 1.
1 through the calculation cycle of the pressure decrease amount Pd (65 m
It is executed by interruption every predetermined time shorter than s).

In the switching valve evaluation routine, when the leak diagnosis is completed (S101: YES), the switching valve 1 is operated so as to gradually release the gas from the evaporation path 4.
The switching operation (communication / interruption) of 2 is repeated (S102). After that, the detection completion flag F used for determining whether or not the responsiveness deterioration of the switching valve 12 has been detected.
Is "0 (decrease in responsiveness not detected)" as the electronic control unit 1
It is determined whether or not it is stored in a predetermined area of the backup RAM in No. 1 (S103).

If an affirmative decision is made in step S103, the condition is that the switching valve 12 is being controlled to the side that shuts off the evaporation path 4 (S104: YES), and 65 m
The pressure drop amount Pd in the evaporation path 4 is calculated for each s (S
105), it is determined whether or not the pressure decrease amount Pd is equal to or greater than the determination value X (S106). And 65ms
The pressure decrease amount Pd calculated for each of the three consecutive judgment values X
It is determined whether or not the following (S107).

In step S107, an affirmative determination is made and during the period when the switching valve 12 is controlled to be in the shut-off state (195 m
s) If the pressure decrease amount Pd continues to be equal to or less than the determination value X, it is evaluated that the responsiveness of the switching valve 12 is decreasing. Then, "1 (decreased responsiveness)" is stored as the detection completion flag F in a predetermined area of the backup RAM in the electronic control unit 11 (S108). In this way, the decrease in the responsiveness of the switching valve 12 is detected.
Then, when the detection completion flag F is set to "1 (decrease in responsiveness detected)", the abnormal lamp 18 is turned on through the electronic control unit 11, and the driver etc. are notified of the responsiveness decrease of the switching valve 12. .

According to this embodiment described in detail above, the following effects can be obtained. (1) After the leak diagnosis, in order to gradually reduce the pressure in the evaporation path 4, the switching valve 12 is compulsorily controlled so that the communication and disconnection between the evaporation path 4 and the atmosphere side are repeated. In this process, when the switching valve 12 shifts from the communication state to the shutoff state, if the responsiveness of the switching valve 12 is deteriorated, the shift is delayed, and the evaporation in the predetermined period (195 ms) after the start of the shift is reduced. The pressure drop amount Pd in the path 4 is maintained to be large. Therefore, by evaluating the responsiveness of the switching valve 12 based on the pressure decrease amount Pd, it is possible to accurately detect the decrease in the responsiveness of the switching valve 12. When a decrease in the responsiveness of the switching valve 12 is detected, the fact is notified to the driver or the like by lighting the abnormal lamp 18, so that prompt measures can be taken against the decrease in the responsiveness of the switching valve 12. it can.

(2) The evaluation that the responsiveness of the switching valve 12 has deteriorated is made by judging whether or not the pressure decrease amount Pd is not less than the judgment value X every 65 ms in the above-mentioned predetermined period. The determination is made when Pd is equal to or greater than the determination value X three times. On the other hand, when the responsiveness of the switching valve 12 is actually decreasing, the pressure decrease amount Pd continues to be equal to or less than the determination value X during the predetermined period (195 ms). Therefore, by performing the evaluation that the responsiveness of the switching valve 12 is degraded as described above, it becomes possible to accurately detect the responsiveness degradation of the switching valve 12.

(3) The responsiveness evaluation of the switching valve 12 is performed at the same time as the periodic communication / blocking of the switching valve 12 for gradually releasing the gas from the evaporation path 4 after the leakage diagnosis. Therefore, the responsiveness of the switching valve 12 can be evaluated while suppressing the rapid release of gas from the evaporation path 4 as much as possible.

(4) The responsiveness evaluation of the switching valve 12 is performed when the switching valve 12 executes the above-described periodic communication / blocking. Therefore, before controlling the switching valve 12 so that the evaporation path 4 and the atmosphere side are shut off in order to calculate the pressure decrease amount Pd, the switching valve 12 is forcibly controlled so that the evaporation path 4 and the atmosphere side communicate with each other. To be done. Therefore, the pressure change in the evaporation path 4 can be accurately displayed during the calculation period (195 ms) of the pressure decrease amount Pd, and the responsiveness of the switching valve 12 based on the pressure decrease amount Pd can be accurately evaluated.

(5) The periodic communication / shutoff of the switching valve 12 and the responsiveness evaluation are started when the leak diagnosis is completed. Therefore, when the leak diagnosis is completed, the switching valve 12 is forcibly controlled so that the evaporation path 4 and the atmosphere side communicate with each other, and immediately thereafter, the switching valve 12 is controlled so as to shut off the evaporation path 4 and the atmosphere side. To be done. Since the responsiveness of the switching valve 12 is evaluated based on the pressure drop amount Pd during a predetermined period (195 ms) after the start of the transition to the shutoff state, the response of the switching valve 12 is obtained at an early stage after the leak diagnosis is completed. It becomes possible to evaluate sex. Therefore, it becomes possible to detect the decrease in the responsiveness of the switching valve 12 as soon as possible after the leak diagnosis.

The above embodiment can be modified as follows, for example. In the present embodiment, when the responsiveness decrease of the switching valve 12 is detected, the abnormality lamp 18 is turned on to notify the fact, but the present invention is not limited to this. For example, when a decrease in the responsiveness of the switching valve 12 is detected, the leak diagnosis is not performed thereafter, and when the gas is released from the evaporation path 4 after the leak diagnosis, the gas containing the evaporated fuel is not released. Release to the atmosphere side may be suppressed.

Although the switching valve 12 and the electric air pump 13 are integrally provided as the electric pump module 10, the switching valve 12 and the electric air pump 13 may be separately provided.

It is not always necessary to evaluate the responsiveness of the switching valve 12 immediately after the completion of the leak diagnosis. For example, the evaluation of the responsiveness of the switching valve 12 may be started after a predetermined time has elapsed after the completion of the leak diagnosis. .

Next, the technical idea which can be understood from the above embodiment will be described below together with its effects. (1) In the diagnostic device for an evaporated fuel processing mechanism according to any one of claims 1 to 5, when the evaluation means evaluates that the responsiveness of the switching valve is low, a notification means for notifying the effect An apparatus for diagnosing an evaporated fuel processing mechanism, further comprising:

According to the above configuration, since it can be known by the informing means that the responsiveness of the switching valve is lowered, it is possible to promptly take measures against the lowered responsiveness of the switching valve.

(2) In the diagnostic apparatus for the evaporated fuel processing mechanism according to any one of claims 1 to 5 and (1) above,
When the responsiveness of the switching valve is evaluated to be deteriorated by the evaluation means, further comprising prohibition means for prohibiting pressurization in the evaporative path for the leak diagnosis thereafter. Evaporative fuel processing mechanism diagnostic device.

According to the above configuration, the leak diagnosis is performed even after it is evaluated that the responsiveness of the switching valve is deteriorated, and the gas is released from the evaporation route to the atmosphere side after the diagnosis. It is possible to prevent the gas containing the evaporated fuel from being released due to the decrease in the responsiveness of the switching valve.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a diagnostic device for an evaporated fuel processing mechanism according to the present embodiment.

FIG. 2 is a schematic diagram showing an internal structure of an electric pump module provided in an evaporated fuel processing mechanism.

FIG. 3 is a schematic diagram showing an internal structure of an electric pump module provided in an evaporated fuel processing mechanism.

FIG. 4 is a time chart showing changes in pressure detected by a pressure sensor and operation modes of a switching valve and an electric air pump when leak diagnosis of an evaporation path is performed.

FIG. 5 is a time chart showing changes in the total flow rate (gas release amount) of the gas released from the evaporation route to the atmosphere side after the leak diagnosis.

FIG. 6 is a time chart showing changes in pressure inside the evaporative path when gas is released from the evaporative path to the atmosphere side after a leak diagnosis.

FIG. 7 is a time chart showing changes over time in the total flow rate (gas release amount) of gas released from the evaporation route to the atmosphere side after a leak diagnosis.

FIG. 8 is a time chart showing changes in pressure inside the evaporative path when gas is released from the evaporative path to the atmosphere side after a leak diagnosis.

FIG. 9 is a time chart showing a change in pressure in the evaporation path when the switching valve repeats the switching operation after the leak diagnosis and the switching valve shifts from the communication state to the cutoff state.

FIG. 10 is a graph showing the amount of pressure decrease in the evaporation path when the switching valve is in the communication state as described above, with respect to each elapsed time.

FIG. 11 is a time chart showing the transition of the pressure in the evaporation path when the switching valve shifts from the communication state to the shutoff state when the switching operation of the switching valve is repeated after the leak diagnosis.

FIG. 12 is a graph showing the amount of pressure decrease in the evaporation path when the switching valve is in the communication state as described above, with respect to each elapsed time.

FIG. 13 is a flowchart showing a procedure for evaluating the response of the switching valve and detecting a decrease in the response.

[Explanation of Codes] 1 ... Engine, 2 ... Fuel tank, 3 ... Intake passage, 4 ... Evaporation passage, 5 ... Canister, 6 ... Vapor passage, 7 ... Purge passage, 8 ... Atmosphere passage, 9 ... Purge control valve, 10 ... electric pump module, 11 ... electronic control device, 12 ... switching valve, 13 ... electric air pump, 14 ... bypass passage, 1
5 ... Check valve, 16 ... Pressure sensor, 17 ... Reference hole, 18 ...
Anomaly sensor.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Tokiji Ito             1 Toyota Town, Toyota City, Aichi Prefecture Toyota Auto             Car Co., Ltd. (72) Inventor Shuichi Hanai             1 Toyota Town, Toyota City, Aichi Prefecture Toyota Auto             Car Co., Ltd. (72) Inventor Akira Ichikawa             1-1, Showa-cho, Kariya city, Aichi stock market             Inside the company DENSO (72) Inventor Kenji Nagasaki             1-1, Showa-cho, Kariya city, Aichi stock market             Inside the company DENSO F-term (reference) 3G044 BA22 BA23 DA04 DA07 EA18                       EA32 EA55 EA57 FA02 FA39                       GA04 GA24

Claims (5)

[Claims] 1. An evaporative fuel provided with an evaporation path for sending evaporated fuel generated in a fuel supply system of an internal combustion engine to an intake system of the engine, and a switching valve which can be switched so as to connect or disconnect the evaporation path and the atmosphere side. It is applied to a processing mechanism, and the leak is diagnosed based on the pressure state when the evaporative path and the atmosphere side are shut off by the switching valve and the inside of the same path is pressurized in this state, and after the diagnosis, the evaporative path In the diagnostic device of the evaporated fuel processing mechanism that controls the switching valve so that the gas is gradually released to the atmosphere side, when the gas is being released from the inside of the evaporation path to the atmosphere side after the leak diagnosis, Control means for controlling the switching valve to shut off the evaporation path and the atmosphere side; and control for the switching valve to shut off the evaporation path and the atmosphere side by the control means. Based on said change in pressure in the evaporation route, diagnostic apparatus for evaporative fuel processing mechanism, characterized in that it comprises an evaluation means for evaluating the response of the switching valve when. 2. The evaluation means, when the switching valve is controlled by the control means so as to shut off the evaporation path from the atmosphere side, a pressure drop amount in the evaporation path is a predetermined value or more for a predetermined period. 2. The evaporative fuel processing mechanism diagnostic device according to claim 1, wherein the responsiveness of the switching valve is evaluated to be lowered based on the existence of the switching valve. 3. The control means connects the evaporation path and the atmosphere side before controlling the switching valve so as to shut off the evaporation path and the atmosphere side for responsiveness evaluation of the switching valve. 3. The diagnostic apparatus for the evaporated fuel processing mechanism according to claim 1, wherein the switching valve is forcibly controlled so that the fuel cells communicate with each other. 4. The control means forcibly controls the switching valve so that the evaporation path and the atmosphere side communicate with each other when the leak diagnosis is completed.
4. The evaporative fuel treatment mechanism diagnostic device according to any one of 3 above. 5. The control means controls the switching valve such that communication / interruption between the evaporation path and the atmosphere side is repeated every predetermined period after the leak diagnosis is completed. A diagnostic device for an evaporated fuel processing mechanism according to any one of claims.